Short answer
CSA "scores" are FMCSA Safety Measurement System (SMS) percentiles in seven safety categories called BASICs, built from 24 months of roadside inspections, crash reports and investigations. They do not set your premium by formula, but underwriters and brokers review your public safety data, so poor results can mean surcharges, declined quotes or lost loads.
- A higher percentile is worse. For most property carriers FMCSA prioritizes intervention at the 65th percentile in Unsafe Driving, Crash Indicator and Hours-of-Service, and at the 80th in the other BASICs.
- Recent violations count three times as much as violations more than a year old, so a clean six months moves the numbers.
What CSA and SMS actually measure
CSA (Compliance, Safety, Accountability) is FMCSA's enforcement program. SMS is the scoring engine inside it. According to FMCSA, the SMS uses roadside inspection and crash data from the last two years plus investigation data, updates monthly, and organizes results into seven BASICs: Unsafe Driving, Crash Indicator, Hours-of-Service Compliance, Vehicle Maintenance, Controlled Substances/Alcohol, Hazardous Materials Compliance, and Driver Fitness.
The SMS groups carriers with similar numbers of safety events, ranks them, and assigns a percentile from 0 to 100, where a higher percentile means worse performance. The current methodology document (version 3.21, revised 2026) also flags carriers with acute or critical violations found during an investigation in the past 12 months.
How violations are weighted
Each violation gets a severity weight from 1 (less severe) to 10 (most severe), plus 2 more if it put the driver or vehicle out of service. It then gets a time weight: 3 if it happened in the last six months, 2 if six to twelve months ago, and 1 if older than that but within 24 months. Severity weights for one inspection in one BASIC are capped at 30 before time weighting.
That is why a bad month hurts quickly and fades slowly, and why out-of-service violations matter more. See what is an out-of-service rate.
| BASIC | General | Hazmat carriers | Passenger carriers |
|---|---|---|---|
| Unsafe Driving, Crash Indicator, HOS Compliance | 65% | 60% | 50% |
| Vehicle Maintenance, Controlled Substances/Alcohol, Driver Fitness | 80% | 75% | 65% |
| Hazardous Materials Compliance | 80% | 80% | 80% |
What the public, brokers and underwriters can see
Not all SMS results are public. The methodology marks the Crash Indicator and Hazardous Materials Compliance BASIC assessments as not publicly available, and full results are visible to enforcement and to carriers logged into their own profiles. Inspection counts, out-of-service rates and other data on the SAFER Company Snapshot are public.
Insurers do not publish how they weigh SMS data, and it is not a fixed formula. In practice, underwriters reviewing a trucking submission typically look at inspection history, out-of-service rates, BASICs at or above threshold, crash history and any safety rating, alongside loss runs and driver MVRs. Brokers screening carriers look at the same public data. After the Supreme Court's May 2026 broker-liability ruling, many brokers have more reason to. See why brokers require $1 million.
Fix the data, not just the score
If an inspection or crash is recorded wrong, or was not your truck, you can request a review through FMCSA’s DataQs system. Clean, accurate data is worth the hour it takes.
What actually improves your numbers
- Pre-trip inspections that catch lights, tires and brakes, which drive Vehicle Maintenance violations.
- ELD and hours discipline.
- Driver qualification files that are complete (see DOT safety rating).
- Fixing defects before re-dispatch, and documenting it.
- Time: older violations lose weight automatically.
For insurance, pair better numbers with a short written safety narrative at renewal. It gives the underwriter a reason to apply credits rather than surcharges.
Common questions
Is there one CSA score?
No. There are separate percentiles for each BASIC, and some are not public. "CSA score" is shorthand.
How long do violations stay in SMS?
SMS uses the last 24 months of inspection and crash data, with older violations weighted less.
Do I need inspections to have percentiles?
Yes. Carriers need a minimum amount of data in a BASIC to be ranked. Small carriers with few inspections often show no percentile at all, which underwriters treat as limited data rather than good data.
Sources
- FMCSA CSA, Measure: The Safety Measurement System. Two years of data, monthly updates, seven BASICs, percentile ranking.
- FMCSA, SMS Methodology (version 3.21, June 2026). Intervention thresholds, severity and time weights, violation cap, non-public BASICs.
- FMCSA SAFER, Company Snapshot. Public inspection, out-of-service and crash data.
This page explains insurance, not law. Have your attorney review indemnity and contract language; our job is making the insurance match it.